This invention generally relates to medical slings, methods of making such slings, kits including such slings, and methods of treating a damaged portion of a patient""s body using such slings.
Urinary incontinence is a disorder that generally affects people of all ages. The inability to control urination can impact a patient both physiologically and psychologically. Urinary incontinence can interfere with a patient""s daily activity and impair quality of life. Stress urinary incontinence is one type of urinary incontinence. Actions including straining, coughing, and heavy lifting can cause those with stress urinary incontinence to void urine involuntarily.
Various physiological conditions cause urinary incontinence in women. Stress urinary incontinence generally is caused by two conditions that occur independently or in combination, intrinsic sphincter deficiency and hypermobility. Intrinsic sphincter deficiency (ISD) is a condition where the urethral sphincter fails to coapt properly. When functioning properly, the urethral sphincter muscles relax to enable the patient to void, and the sphincter muscles are otherwise constricted to retain urine. ISD may cause urine to leak out of the urethra during stressful actions. Hypermobility is a condition where the pelvic floor is weakened or damaged causing the bladder neck and proximal urethra to rotate and descend in response to increases in intraabdominal pressure. When intraabdominal pressure increases (due, for example, to strain resulting from coughing), the hypermobility condition may cause urine leakage. Some women suffer from a combination of ISD and hypermobility.
The methods for treating stress urinary incontinence include placing a sling to either compress the urethral sphincter or placing a sling to support, elevate or provide a xe2x80x9cback stopxe2x80x9d to the bladder neck and proximal urethra. Providing support to the bladder neck and proximal urethra maintains the urethra in the normal anatomical position and elevation places the urethra above the normal anatomical position. The xe2x80x9cback stopxe2x80x9d prevents descent according to the hammock theory such that the back stop prevents the bladder neck from descending upon application of strain.
Generally, slings are employed to support anatomical structures. Slings may be made from one or more materials derived from mammalian tissue(s), synthetic material(s), or from a combination of mammalian tissue(s) and synthetic material(s).
After implantation in a patient, slings made from mammalian tissues typically require a six to twelve month period to be absorbed by the patient""s body, after which the implanted mammalian tissue is not recognizable from the patient""s surrounding tissue. Mammalian tissue slings include tissue harvested from the patient or a donor. In some instances, the mammalian tissue may be human cadaveric tissue.
The success of mammalian tissue sling surgery is limited when the tissue sling shifts after surgery from the implantation site causing the sling to become incorporated by patient tissue in an improper position. Improper sling placement can also result when the sling comprised of mammalian tissue shrinks after placement inside the patient. Excess tension, shifting, and shrinkage may occur independently or in combination to cause failed sling retention.
The present invention relates to slings disposed with cuts, methods of making such slings, medical kits including such slings, and methods of treating a damaged portion of a patient""s body using such slings. Various known surgical procedures employ slings to support anatomical structures. Exemplary surgical applications include the treatment of urinary incontinence, the repair of herniation, and orthopedics generally.
In accordance with the invention, cuts are disposed through the sling material to provide open areas in the sling which enable rapid tissue ingrowth into the sling material while maintaining a high tensile strength. The cuts can be slits, holes, and apertures. The sling with the cuts according to the invention maintains a substantially constant width during and after implantation in a patient""s body. The risk of pressure necrosis or erosion of the damaged portion of the patient""s body caused by uneven sling pressure is reduced because the sling width remains substantially constant even when the sling is stretched longitudinally during the implantation procedure.
The benefits of such a sling, which can comprise synthetic material, mammalian tissue, or a combination of synthetic and mammalian tissue material with cuts disposed through the material, include rapid fibrosing of the sling, a shortened healing period, and little or no sling movement after implantation. In accordance with the invention, when a sling is employed to treat female urinary incontinence connective tissue resembling scar tissue will begin to infiltrate one or more open areas disposed in the sling (which is positioned underneath the patient""s urethra). The formation of scar tissue generally adds bulk that compresses the urethra and provides the support to improve patient continence. The scar tissue that infiltrates the sling holds the sling at the site of implantation and inhibits or prevents its movement.
In general, in one aspect, the invention involves a sling for use in a medical application. The sling is made of a sheet of synthetic material, mammalian tissue, or a combination of mammalian tissue and synthetic material. The sheet has a longitudinal axis with a first end portion and a second end portion. The second end portion of the sheet is disposed opposite and away from the first end portion along a longitudinal axis. The sheet also includes a first side and a second side, the second side is disposed opposite and away from the first side by a distance and along a perpendicular axis. The perpendicular axis is perpendicular or substantially perpendicular to the first axis (i.e., for example a longitudinal axis). The perpendicular axis intersects the longitudinal axis at the midpoint or substantially the midpoint of the longitudinal axis. The sheet further includes one or more cuts disposed substantially along at least a portion of the second axis (i.e., for example a perpendicular axis). The cuts are disposed such that upon exposure to tensioning force applied to the sheet substantially along the longitudinal axis during the medical application, the distance along the perpendicular axis remains substantially constant.
Embodiments of this aspect of the invention can include the following features. The cuts disposed on the sling may be a slit disposed through the sheet of material. The slits may be disposed such that at least some of the slits open upon exposure to the tensioning force applied during the medical application. The open slits provide open areas on the sling which permit tissue crosslinking and ingrowth therein when implanted inside the body of a patient.
Alternatively, the cuts may comprise any aperture disposed through the sheet of the sling. Upon exposure to the tensioning force applied during the medical application, at least some, and generally all, of the apertures on the sling remain open. The apertures that remain open provide open areas on the sling. The open areas permit tissue crosslinking and ingrowth into the cuts when the sling is implanted inside the body of a patient.
According to the invention, the cuts may be disposed substantially along the perpendicular axis of the sling. In some embodiments the cuts may be equidistant from one another.
In other embodiments, a line may be disposed, as a visual indicator, substantially along at least a portion of the perpendicular axis of the sling. The line can be made by applying a surgical ink to the sling material.
The material of the sling may be derived from mammalian tissue source(s), synthetic material(s), or a combination of mammalian tissue(s) and synthetic material(s). The mammalian tissue source may be human, human cadaveric, or tissue-engineered human tissue. The mammalian tissue may alternatively be from an animal source. Suitable sources of animal tissues may include porcine, ovine, bovine, and equine tissue sources. The material may be an omnidirectional material, a material that has equivalent tensile strength from any direction, such as pericardium or dermis. Alternatively, the material of the sling may be an oriented material, a material that has a single direction where the tensile strength of the material is the highest. Oriented materials may include rectus fascia and/or facia lata.
The synthetic material may be a solid material, a weave, a braid, a mesh, or some other suitable construction. The synthetic material source may be nylon, polyethylene, polyester, polypropylene, fluoropolymers, copolymers thereof, and other suitable synthetic materials. The material may be a synthetic material that is absorbable by the patient""s body. Suitable absorbable synthetic materials may include polyglycolic acid, polylactic acid, and other suitable absorbable synthetic materials. The synthetic material may be oriented and have a single direction where the tensile strength of the material is highest. Alternatively, the material may be omnidirectional such that any direction of the synthetic material may have equivalent tensile strength.
The cuts can be formed through a sheet made of oriented tissue material along the grain, i.e., along a single direction where the tensile strength of the material is the highest. By disposing the cuts along the grain of the oriented material, the strength of the sheet may be substantially maintained. Upon exposure to tensioning force applied to the sheet substantially along the longitudinal axis, the distance along the perpendicular axis of the oriented sheet remains substantially constant. Likewise, by forming cuts through and along the highest tensile strength direction of a sheet of synthetic sling material, the strength of the synthetic sheet may be substantially maintained.
In one embodiment, one or more fasteners are disposed on the sheet of sling material. The fasteners may be disposed in regions of the sheet where there are no cuts. The fasteners may be disposed, for example, at each of the first end portion and the second end portion of the sheet. Alternatively, or in addition, one or more eyelets may be disposed through both the first end portion and the second end portion of the sheet. In one particular embodiment, a fastener, for example a suture, is secured to a sling by threading it through an eyelet disposed through the sling.
The sling of the invention may be made of a sheet that is in a shape suitable for a medical application. Suitable shapes may include rectangular and substantially rectangular. The sling may be octagonal, hexagonal, trapezoidal, elliptical, or some other shape that is suitable to the slings intended placement location within the body. In some embodiments, the sheet has elongated members, which extend substantially from a central portion of the sheet. The elongated members may be anchored to an anatomical structure in the patient without use of a suture.
In general, in another aspect, the invention relates to a method of making a sling by forming one or more cuts in a sheet of material provided in a shape suitable for use in a medical application. The sheet provided may be derived from mammalian tissue(s), synthetic material(s), or a combination of mammalian tissue(s) and synthetic material(s). The sheet includes a first end portion and a second end portion. The second end portion of the sheet is disposed opposite and away from the first end portion along a longitudinal axis. The sheet also includes a first side and a second side. The second side is disposed opposite and away from the first side by a distance and along a perpendicular axis. The perpendicular axis is substantially perpendicular to the longitudinal axis. The perpendicular axis intersects the longitudinal axis at substantially the midpoint of the longitudinal axis. The one or more cuts are formed substantially along at least a portion of the perpendicular axis of the sheet. The cuts are formed in the sheet such that the distance along the perpendicular axis of the sheet remains substantially constant upon exposure to the tensioning force applied to the sheet substantially along the longitudinal axis during a medical application.
Embodiments of this other aspect of the invention can include the following features. The method of making the sling can further comprise forming a line substantially along at least a portion of the perpendicular axis of the sling. The line can be formed by applying surgical ink to the sling material. The line may be used as a visual indicator during a medical application.
The method of making the sling can further comprise disposing one or more fasteners at the first end portion of the sheet. One or more fasteners may also be disposed at the second end portion of the sheet. The fasteners may be disposed on regions of the first end portion and the second end portion of the sheet where cuts are not disposed through the material.
The method of making the sling can further comprise sterilizing the material and sterilizing the sling according to methods known in the art to make the sling suitable for use in various medical applications. The method of making the sling may include packaging the sling in a sterile holder. According to methods of the invention, the sling may be packaged under conditions that are dry and protective from ultra-violet light.
In general, in a further aspect, the invention involves a method of treating a damaged portion of a patient""s body. A sling is provided and then used. The sling is made of a sheet of material that has cuts disposed through the sheet to provide open areas upon implantation inside the patient""s body. The material of the sheet may be derived from mammalian tissue(s), synthetic material(s), or a combination of mammalian tissue(s) and synthetic material(s). The sheet includes a first end portion and disposed opposite and away from the first end portion along a longitudinal axis is a second end portion. The sheet also includes a first side and disposed opposite and away from the first side by a distance and along a perpendicular axis is a second side. The perpendicular axis is substantially perpendicular to and intersects the longitudinal axis at substantially the midpoint of the longitudinal axis. The sheet further includes one or more cuts disposed substantially along at least a portion of the perpendicular axis. The first end portion of the sling sheet is secured to a first anatomical structure in the body of the patient. Tensioning force is applied substantially along the longitudinal axis of the sheet. The second end portion of the sling is secured to a second anatomical structure in the body of the patient. The sling is secured inside the body of the patient such that it""s perpendicular axis lies substantially along a portion of the patient""s body. The one or more cuts are disposed such that the distance along the perpendicular axis of the sheet remains substantially constant when the sling is secured. The secured sling supports a damaged portion of the patient""s body.
The method of using the sling of the invention may further comprise securing the first end portion to an anatomical structure using a surgical fastener. Surgical fasteners employed to secure the sling may include a suture, a clip, a bone anchor, a staple, or other suitable fasteners.
The sling may be secured to an anatomical structure in the body of the patient. Suitable anatomical structures include: bone, fascia, ligament, or muscle.
The method of using the sling can further comprise centering the sling at the damaged portion of a patient""s body using a line disposed substantially along at least a portion of the perpendicular axis as a visual indicator. The line may provide a visual indication of where the one or more cuts are disposed on the sling and the line may be employed to help align the cuts with the damaged portion of the patient""s body.
When the cuts are slits, at least some of the slits can be open when supporting the damaged portion of the patient""s body. Alternatively, when the cuts are apertures, at least some of the apertures can remain open when supporting the damaged portion of the patient""s body. The open cuts provide open areas on the sling which permit the patient""s tissue to crosslink and grow into the open areas on the sling once the sling is secured inside the body of the patient. The scar tissue ingrowth both secures the sling inside the patient""s body and provides support to the areas of the body into which the tissues grow.
The method may further comprise evenly distributing pressure on a damaged portion of a patient""s body with the secured sling material. In one embodiment, the sling is employed to treat a female patient with urinary incontinence. The sling material may be implanted to evenly distribute pressure on a patient""s urethra. The sling may be delivered and implanted to treat female urinary incontinence according to transvaginal, transabdominal, or combined transvaginal and transabdominal procedures.
In one embodiment, the sling is employed to treat a patient suffering from ISD. The sling may be implanted such that the one or more cuts on the sling contact the underside of the patient""s sphincter muscle, the first side of the sling contacts the under portion of the distal bladder neck and second side of the sling contacts the under portion of the urethra. The sling can be implanted such that the sling material evenly distributes pressure on a patient""s sphincter muscle without applying pressure to the urethra or bladderneck. Alternatively, the method may be employed to treat a patient with bladderneck hypermobility and the cuts on the sling may be placed adjacent to the patient""s mid urethra.
The patient""s body can absorb the material of the sling after implantation of the sling in the body. The sling material absorbed by the patient""s body may be made from mammalian tissue. Alternatively, synthetic absorbable sling material may be absorbed by the patient""s body after implantation therein.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.